Base Units: The fundamental units in the SI system from which all other units are derived, including meter, kilogram, second, ampere, kelvin, mole, and candela.
Derived Units:Units that are formed by combining base units according to algebraic relationships; examples include newton for force and joule for energy.
Prefixes: Standardized additions to unit names that indicate decimal multiples or fractions of a unit, such as kilo- ($10^3$) or milli- ($10^{-3}$).